Hydrochemistry and genesis of the Honghegu hot spring in Mile, Yunnan Pronince

The purpose of this work was to clarify the genesis of Honghegu hot spring in Mile， Yunnan and the influence of exploitation of drilling hot water on the spring， providing a reasonable basis for the development of hot water resources in this area. Hydrochemical analysis and isotopic tests were performed to the hot spring， cold spring and drill-hole hot water in the study area. Results show that degree of mineralization of the spring is about 232-328 mg.L-1， the pH is slightly acidic， with H2SiO3 of 25.45-34.44 mg.L-1 and Sr of 0.29-0.44 mg.L-1. The hot water belongs to the HCO3-Ca type， while the cold water belongs to the HCO3-Ca.Mg type. The temperature of the geothermal reservoir is 65-70 ℃. Hydrogen and oxygen isotopes indicate that hot spring water comes from meteoric precipitation. The elevation of the recharge area of the hot spring is estimated as about 2，100 m. The hot spring is controlled by the fault zone， supplied by atmospheric precipitation. Heated by earth's heat flow， it flows out of the surface along the fault zone. Due to water isolation of basalt and the direction of groundwater flow， mining of borehole hot water and self-flowing hot water has little effect on the hot spring.